1. Technical Field
The present invention relates to a USB host, a control method thereof; computer program, a USB hub, and a USB device.
2. Related Art
From the past, various studies have been proposed regarding a USB host performing communication with a USB device. For example, JP-A-2007-098850 discloses a color laser printer functioning as a USB host, in which when a USB memory, which is a USB device, is connected to a USB port thereof, a determination is made as to whether or not the USB memory is a USB key that allows execution of printing so that the execution of printing is allowed when the USB memory is the USB key while the execution of printing is inhibited when the USB memory is not the USB key.
However, in some types of PC peripherals, there is a case where one having the same device configuration is classified and sold as a higher grade model of high price and as a lower grade model of low price. In such a case, the higher grade model has no restrictions placed on its capability that can be exhibited by the device configuration while the lower grade model has restrictions on its capability. For example, if there is a scanner having a device configuration that it is capable of reading documents of a predetermined size with a scan speed of 60 pages per minute, the higher grade model is able to perform scanning with a scan speed of 60 pages per minute with no restrictions placed on its capability while the lower grade model is only able to perform scanning with a scan speed of 30 pages per minute because of the restrictions on its capability. Here, a case may be considered in which a user who purchased the lower grade model is discontented with the scan speed to purchase a higher grade model. However, in such a case, because the user has to purchase two scanners having substantially the same device configuration, it is not desirable to the user. In this respect, it may be desirable to solve the user's discontent with the scan speed by upgrading the lower grade model to the higher grade model. As one method of upgrading the scanner of the lower grade model to one of the higher grade model, a method that uses the USB key as disclosed in JP-A-2007-098850 may be considered. Specifically, the scanner is regarded as a USB host, and when a USB memory, which is a USB device, is connected to a USB port thereof, a determination is made as to whether or not the USB memory is the USB key that allows upgrading thereof so that the restriction on its capability is cancelled when the USB memory is the USB key.
However, in such a case, it is necessary to construct the device configuration so that the scanner functions as the USB host. Because it is a general use form that the PC functions as the USB host and the scanner functions as the USB device, it may be troublesome to construct the device configuration so that the scanner also functions as the USB host.